1. Field of the Invention
The present invention relates to a radiation image capturing apparatus for capturing a radiation image of a subject using a radiation image information detector.
2. Description of the Related Art
In the medical field, for example, radiation image capturing apparatuses are extensively used, which acquire radiation image information by irradiating a subject (patient) with radiation emitted from a radiation source, and detecting the radiation that has passed through the subject with a radiation image information detector.
In a radiation image capturing apparatus provided with a radiation image information detector, an image signal (radiation image information) produced by the radiation image information detector is read out from the detector, amplified by an amplifier, and transmitted to an image processing apparatus that performs image processing on the image signal. Since the radiation image information detector generates the image signal from a very small amount of charge, the image signal tends to be affected by even small temperature variations in the radiation image information detector, the amplifier, and the like.
Japanese Laid-Open Patent Publication No. 2002-022841 discloses a radiation image capturing apparatus capable of producing an image signal that is particularly stable with respect to temperature variation of the amplifier. This radiation image capturing apparatus includes, as shown in FIG. 9, a glass sensor substrate 100 on which a plurality of pixels are formed. Each pixel is a conversion unit that includes a photoelectric conversion element and a thin film transistor (TFT). A phosphor layer 102 is further formed on the sensor substrate 100.
A flexible substrate 103, which serves as signal lines, is connected to the sensor substrate 100 and also to a signal processing circuit board 104, and a detection integrated circuit 110, which is an amplifying means, is mounted on the flexible substrate 103. A cooling fin 105 is attached to the integrated circuit (IC) 110, with a heat transmitting member 106 disposed between the IC 110 and the cooling fin 105, in order to release heat generated by the integrated circuit 110. The cooling fin 105 is supported by sleeves 109 that are attached to the flexible substrate 103 by an elastic member 107 and a fastening plate 108 arranged on the opposite side of the flexible substrate 103 to the integrated circuit 110.
However, the apparatus described in Japanese Laid-Open Patent Publication No. 2002-022841 requires a substantially large cooling fin 105 to achieve sufficient heat release, and thus raises a problem in that the size of the apparatus may have to be increased to contain the large cooling fin 105.
Especially in X-ray breast image capturing apparatuses (mammography apparatuses) that capture a radiation image of a breast of a subject by exposing the breast to radiation, it is difficult to increase the size of the image capturing base in which the radiation image information detector is housed, due to the configuration of the apparatus. Hence, the heat release technique described in the Japanese Laid-Open Patent Publication No. 2002-022841 is not easily applied to such apparatuses.